package com.example.ex00_test;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import android.util.Log;

/**
 * @author carlos carlosk@163.com
 * @version 创建时间：2012-5-17 上午9:48:35 类说明
 */

public class AESUtils {
	public static final String TAG = "AESUtils";

	public static String encrypt(String seed, String clearText) {
		// Log.d(TAG, "加密前的seed=" + seed + ",内容为:" + clearText);
		byte[] result = null;
		try {
			byte[] rawkey = getRawKey(seed.getBytes());
			result = encrypt(rawkey, clearText.getBytes());
		} catch (Exception e) {
			e.printStackTrace();
		}
		String content = toHex(result);
		Log.d(TAG, "加密后的内容为:" + content);
		return content;

	}

	public static String decrypt(String seed, String encrypted) {
		// Log.d(TAG, "解密前的seed=" + seed + ",内容为:" + encrypted);
		byte[] rawKey;
		try {
			rawKey = getRawKey(seed.getBytes());
			byte[] enc = toByte(encrypted);
			byte[] result = decrypt(rawKey, enc);
			String coentn = new String(result);
			Log.d(TAG, "解密后的内容为:" + coentn);
			return coentn;
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}

	}

	private static byte[] getRawKey(byte[] seed) throws Exception {
		KeyGenerator kgen = KeyGenerator.getInstance("AES");
		SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
		sr.setSeed(seed);
		kgen.init(128, sr);
		SecretKey sKey = kgen.generateKey();
		byte[] raw = sKey.getEncoded();

		return raw;
	}

	private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
		SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
		// Cipher cipher = Cipher.getInstance("AES");
		Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
		cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec(
				new byte[cipher.getBlockSize()]));
		byte[] encrypted = cipher.doFinal(clear);
		return encrypted;
	}

	private static byte[] decrypt(byte[] raw, byte[] encrypted)
			throws Exception {
		SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
		// Cipher cipher = Cipher.getInstance("AES");
		Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
		cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec(
				new byte[cipher.getBlockSize()]));
		byte[] decrypted = cipher.doFinal(encrypted);
		return decrypted;
	}

	public static String toHex(String txt) {
		return toHex(txt.getBytes());
	}

	public static String fromHex(String hex) {
		return new String(toByte(hex));
	}

	public static byte[] toByte(String hexString) {
		int len = hexString.length() / 2;
		byte[] result = new byte[len];
		for (int i = 0; i < len; i++)
			result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
					16).byteValue();
		return result;
	}

	public static String toHex(byte[] buf) {
		if (buf == null)
			return "";
		StringBuffer result = new StringBuffer(2 * buf.length);
		for (int i = 0; i < buf.length; i++) {
			appendHex(result, buf[i]);
		}
		return result.toString();
	}

	private static void appendHex(StringBuffer sb, byte b) {
		final String HEX = "0123456789ABCDEF";
		sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
	}
}